Coils are generally essential circuit constituent parts and are indispensable parts for some circuits to be constituted. For example, oscillation circuits utilizing LC resonance or tuning circuits contained in a transmitter-receiver could not be implemented without using the coils.
However, the coils contained in the circuit generate magnetic fluxes, so that there is a need for such a design as to prevent the magnetic fluxes from affecting the surrounding components. For example, two coils must be disposed away from each other on a printed wiring board, or if approximate arrangement of a plurality of coils is desired, the direction of the magnetic fluxes must be allowed for in order to ensure a proper arrangement.
FIG. 5 illustrates three coils adjacent to one another, with the direction of the arrangement contrived. As shown in the diagram, the three coils are arranged in such a manner that two adjacent coils are disposed at 90 degrees relative to each other so as to allow magnetic fluxes generated from the adjacent coils to be orthogonal to each other. By allowing the magnetic fluxes generated from the adjacent coils to be orthogonal to each other in this manner, it is possible to suppress the magnetic coupling between the coils to a minimum.
By the way, such a conventional method allowing the magnetic fluxes to be orthogonal to each other as a result of the contrived direction of arrangement of the coils to minimize the magnetic coupling between the coils, is limited to the case where the coils are arranged on the printed wiring board.
In case spirally shaped inductor conductors are formed on the semiconductor substrate by use of a thin film formation techniques, the direction of generation of the magnetic fluxes is limited to the direction orthogonal to the semiconductor substrate. For this reason, the adjacently shaped coils in the form of inductor conductors are magnetically coupled with one another, so that it is inconvenient when it is desired that they be electrically separated as circuit elements. In particular, in cases where passive elements such as inductor conductors together with various active elements are formed on the semiconductor substrate, it is typical to reduce the size of the entire circuit by using the semiconductor fabrication technique, with the result that it becomes difficult to arrange in a fully separate manner a plurality of inductor conductors contained in the circuit.
FIG. 6 is a diagram for explaining the state of the magnetic fluxes generated from the semiconductor circuit containing inductor conductors formed on the semiconductor substrate. When a current flows into the inductor conductors within the semiconductor circuit shown in the diagram, magnetic fluxes occur in the direction substantially orthogonal to the surface of the semiconductor substrate as indicated by an arrow a of the diagram. These magnetic fluxes affect the actions of the other semiconductor elements formed on the semiconductor substrate, often causing noises or malfunctions.